The Canon EF 50mm f/1.0L USM lens was evaluated and was compared to the
EF 50mm f/1.4 and EF 50mm f/1.8 with respect to resolution, MTF and bokeh
performance. The primary question I wanted to answer was: Would the 1.0L
outperform the f/1.4 USM lens at f/1.4? The short answer is: No.

Resolution and 50% MTF Performance
DataLink
to Methods Used The graphs show the best value obtained with
3 or 4 replicates.

I also compared autofocus performance variability by taking 6 autofocus
exposures with each lens at f/2 with an EOS-1v:

Bokeh

Click on the left image below to compare performance of the three 50mm
lenses to diffusely blur backgrounds and to compare out of focus aperture
diaphragm patterns in backgrounds. Click on the image on the right below
to compare the EF 85mm f/1.2L to the EF 50mm f/1.0L for their performance
in producing diffusely out of focus backgrounds.

EF 50mm f/1.0L lens compared to other EF
50mm lenses

EF 85mm f/1.2L lens compared to EF 50mm
f/1.0L lens. The combined telephoto effect and wide aperture of the 1.2L
lens gives much more diffuse, out of focus backgrounds than with the EF
50mm f/1.0L at f/1.0

Linear Distortion

All three lenses have mild barrel distortion.

Lens Data

EF 50mm
f/1.0L USM

EF 50mm f/1.4
USM

EF 50mm f/1.8
II

Lens elements/groups

11/9

7/6

6/5

Blade number in aperture diaphragm

8

8

5

Max diameter x length

91.5mm x 81.5mm

73.8mm x 50.5mm

68.2mm x 41mm

Weight

985 g

290 g

130 g

Motor

USM

Micro USM

Micro Motor

Price, $ USD

$2500Historic, No
longer in production

$310

$75

Summary / Conclusions

EF 50mm f/1.0L USMThis
heavy, complex and well-constructed lens gave disappointing performance. I
had hopes that it would provide excellent optical performance at f/1.4 for
some of my applications. The EF 50mm f/1.4 lens at f/1.4 produced images
almost indistinguishable from those produced by the 1.0L lens at the same
aperture. At f/1.0, images were soft to the point of being almost useless
for any uses I would have for images. This lens may be a collectors item
because it is rare and no longer in production. However, because of its
poor performance at apertures wider than f/1.4 and the improved
performance of high ISO digital cameras, there is little or no
photographic rationale to own one.

EF 50mm f/1.4 USMI
am not alone in considering this the finest EF 50mm prime that Canon has
made to date. It is well built, compact and focuses fast. Optical
performance (resolution, microcontrast and bokeh) is superb. It has the
most accurate and consistent autofocus of the lenses tested.

EF 50mm f/1.8 IIThis
is a cheaply constructed (largely plastic, no metal mount) lens that is
very small and lightweight. Optical performance on the lens tested was
superb, although there was considerable more variability in autofocus
function than with the other two lenses. I plan to continue to carry it in
my lightweight kit with a 5x consumer zoom for times when I need to shoot
unplanned portraits at f/2 or f/2.8. Users on internet photo forums report
considerable lens to lens variability in quality. I appear to have
purchased a great performer.